1. Field of the Invention
The present invention relates to a method for producing edge-functionalized graphite or graphene with fluoro groups via a mechanical process.
2. Description of the Related Art
Graphene has attracted attention as the most promising new material due to its excellent physical and electrical properties. There have been a number of reports on methods for the production of graphene with outstanding physical properties. Such methods can be classified into, for example, mechanical exfoliation, chemical exfoliation, exfoliation-reintercalation-expansion, chemical vapor deposition, epitaxial synthesis, and chemical synthesis.
Although mechanical exfoliation allows graphene to possess its own excellent characteristics, there is a disadvantage in that the final yield of graphene is extremely low. For this reason, the application of mechanical exfoliation is limited to studies on the characterization of graphene in laboratory.
Graphene produced by chemical vapor deposition was reported to exhibit excellent characteristics. However, chemical vapor deposition requires the use of heavy metal catalysts, involves very complicated processing steps, and is disadvantageous from an economic viewpoint, limiting its use for mass production.
Epitaxial synthesis causes poor electrical properties of graphene and requires very expensive substrates.
Chemical synthesis is the most commonly used method for graphene production. According to this method, graphite is chemically oxidized, the graphite oxide is subjected to sonication to obtain graphene oxide, and the graphene oxide is reduced to graphene. Functionalization of the graphite oxide over the entire area leads to poor physical and electrical properties of the graphite oxide. Further, it is difficult to predict to what extent and with what kind of functional groups the graphite oxide is functionalized, and as a result, a secondary reaction of the graphite oxide is substantially impossible to predict. Furthermore, the final product graphene produced from the oxidized graphite loses its excellent characteristics, which limits its use in various application fields, such as transparent electrodes.
Korean Patent No. 10-1245815, issued to the present inventors, discloses a method for producing edge-functionalized graphite via a mechanochemical process, the method including mechanically pulverizing graphite in the presence of one or more surrounding materials. This method enables the production of graphene on a large scale and the introduction of various kinds of functional groups at the edges of graphite. However, the method was not applicable to the production of graphite in which fluoro groups are introduced at the edges by using fluorine or a fluorocarbon compound.